/Engine/Source/Runtime/SignalProcessing/Public/DSP/VoiceProcessing.h
InOnsetThreshold is the minimum amplitude of a signal before we begin outputting audio, in linear gain. InReleaseThreshold is the amplitude of the signal before we stop outputting audio, in linear gain. AttackDurationInSamples is the amount of samples we average over when calculating our amplitude when the in audio is below the threshold. ReleaseDurationInSamples is the amount of samples we average over when calculating our amplitude when the input audio is above the threshold.
FSilenceDetection ( float InOnsetThreshold, float InReleaseThreshold, int32 AttackDurationInSamples, int32 ReleaseDurationInSamples )